1. Field of the Invention
The present invention relates to a plasma display device, and more particularly, to a plasma display device employing a gas mixture of helium and rare gases as a discharge gas.
2. Description of the Related Art
The plasma display device, which displays images utilizing gas discharges exhibits excellent luminance and contrast, and has a wide view angle. The plasma display device forms images by applying AC or DC voltages to electrodes to discharge a gas to thereby emit ultraviolet rays, and the emitted ultraviolet rays excite fluorescent materials to emit light.
The gas typically used as a plasma discharge gas is a mixture of Ne and Xe, or a mixture of He and Xe, and in this case the content of Xe is about 1-5 vol %. When the gas mixture as above is used, the reaction of Xe prevails at the time of discharges, and vacuum ultraviolet rays of wavelengths from about 147 to 200 nm are emitted. Accordingly, the prior plasma display device is provided with fluorescent materials to be excited by the ultraviolet rays whose wavelengths are from about 147 to 200 nm.
However, when a mixture of Ne--Xe, or He--Xe is employed as a discharge gas, in addition to the ultraviolet rays, intense near infrared rays whose wavelengths are from about 800 to 1,000 nm are emitted from Xe, and such near infrared rays may abnormally operate other nearby appliances which are operated by remote control.
Therefore, the plasma display must be provided with a filter for shielding the near infrared rays. Such a filter is known to not only increase the production cost but also to decrease the luminance of an image by at least 30%. In addition, there is a problem in that when a mixture of Ne and Xe is used as a discharge gas, visible light including intense yellow or red color is emitted from Ne gas, and therefore the color purity of displayed images is deteriorated.
Further, as the pressure of the gas mixture increases, the discharge characteristics of the Ne--Xe or He--Xe mixture are very unstable.